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Mortality and Morbidity after groin hernia surgery
- the role of nationwide registers in
finding and analysing rare outcomes
Hanna Nilsson
Department of Surgical and Perioperative Sciences, Section
of Surgery
901 87 Umeå
Umeå 2013
Copyright©Hanna Nilsson
ISBN: 978-91-7459-755-4.
ISSN: 0346-6612-1614
Front cover: by Anna Erlandsson
Printed by: Print & Media
City:Umeå, 2013
i
To Ebba and Anton
“Nothing so prevents the occurrence of complications as
one´s awareness and fear of them”
Robert Bendavid, 1998
ii
ABSTRACT
Introduction: Groin hernia surgery is one of the most common surgical procedures
world-wide. Although mainly uncomplicated, the large volume of these operations
makes it important to consider severe postoperative complications. The Swedish
Hernia Register (SHR) started in 1992 and has grown to include more than 95% of
all groin hernia operations performed in Sweden empowering it to be merged with
other registers in population-based studies. The aim of this thesis is to merge SHR
with other nation-wide registers to analyse postoperative mortality, cardiovascular
morbidity, surgical hazards, as well as to study the influence of prostatectomy upon
the risk for subsequent groin hernia surgery.
Methods: SHR was interlinked with the Cause of Death Register to find standardised
mortality ratio, the National Prostate Cancer Register to find incidence of groin
hernia surgery after prostatectomy compared to a control group and with the National
Patient Register to find morbidity within 30 days of groin hernia surgery. In paper II,
medical records of deceased patients were retrieved and scrutinised.
Results: Elective groin hernia surgery was found to be a low risk procedure even for
elderly patients. The mortality risk within 30 days of emergency surgery was raised
sevenfold compared to that of the background population. Women had a threefold
increased risk of postoperative mortality compared to men. Patients with bowel
obstruction, not examined for groin hernia in the emergency room, were subject to
more radiological examinations and were operated significantly later than patents
with a clinical diagnosis of groin hernia. Compared to men, significantly fewer
women were examined for groin hernia in the emergency ward, 61% vs. 78%,
(P=0.04). High age, co-morbidity, emergency operation, and regional anaesthesia
were risk factors for cardiovascular events. Compared to open anterior mesh repair,
all other methods were associated with increased risk of surgical complication, intra-
operatively or postoperatively. A threefold increase in groin hernia surgery was seen
after radical prostatectomy, conventional as well as minimally invasive.
Discussion: Women are significantly overrepresented concerning mortality after
groin hernia surgery. This thesis shows the importance of nation-based registers in
the analysis of infrequent phenomena in surgical care.
Keywords: Groin hernia, Inguinal Hernia, Femoral Hernia, Mortality, Morbidity,
Prostatectomy
ISBN: 978-91-7459-755-4
iii
List of papers included
This thesis is based upon the following papers that will be referred to by
their roman numerals in the text:
I Nilsson H, Stylianidis G, Haapamaki M, Nilsson E, Nordin P.
Mortality after groin hernia surgery.
Ann Surg. Apr 2007;245(4):656-660.
II Nilsson H, Nilsson E, Angeras U, Nordin P.
Mortality after groin hernia surgery: delay of treatment and
cause of death.
Hernia. Jun 2011;15(3):301-307.
III Nilsson H, Stranne J, Stattin P, Nordin P.
Incidence of Groin Hernia Repair After Radical Prostatectomy
A Population-Based Nationwide Study.
Ann Surg. Jun 6 2013. (Epub ahead of print)
IV Nilsson H, Sandblom G, Angerås U, Nordin P.
Serious adverse events within 30 days of groin hernia surgery
Manuscript
iv
Table of contents
Abstract ii
List of papers included iii
Table of Contents iv
Abbreviations v
Definitions in short vi
Introduction 1 History, definition and prevalence of groin hernia 1
Symptoms and indication for surgery 2
Gender differences 4
Groin anatomy 5
Anatomy and prostatectomy 7
Methods of repair 8
Open anterior repair 8
The tension-free hernioplasty 10
Preperitoneal repair 12
Laparoscopic repair 12
Methods of anesthesia 14
Complications of groin hernia repair 15
Swedish Hernia Register 16
Register studies 18 Aims of the thesis 23
Methodological considerations 24
Statistical considerations 27
Results 28
Paper I 28
Paper II 29
Paper III 30
Paper IV 31 Conclusion 32
General Discussion 33
Strength and weaknesses 33
Main findings 34 Future Perspective 36
Sammanfattning på Svenska 37
Acknowledgement 40
References 42
Appendices (Paper I-IV) 53
v
Abbreviations
EHS European Hernia Society
HR Hazards Ratio
HRT Hormone Replacement Theory
ICD International Classifications of Diseases
IH Inguinal Hernia
MIRP Minimally Invasive Radical Prostatectomy
NPCR National Prostate Cancer Register
NPR Swedish National Patient Register
OR Odds Ratio
PCa Prostate Cancer
PCBaSe Prostate Cancer Base Sweden
PPV Patent Processus Vaginalis
RCT Randomised Controlled Trials
RRP Radical Retropubic Prostatectomy
RT Radiation Therapy
SHR Swedish Hernia Register
SMR Standardised Mortality Ratio
ASIS Anterior Superior Iliac Spine
TAPP Trans-Abdominal PrePeritoneal laparoscopic repair
TEP Totally ExtraPeritoneal laparoscopic repair
TIPP Trans-Inguinal PrePeritoneal repair
vi
Definitions in short
Reducible hernia A hernia that reduces into the abdominal
cavity when lying down or when massaged if
standing.1
Incarcerated hernia A hernia that cannot be reduced into the
abdominal cavity with manual pressure.
Strangulated hernia A hernia with impairment or absence of blood
supply to the content of the hernia sac.
Sliding hernia A hernia containing a retroperitoneal organ,
with or without its mesentery,2 and where the
abdominal viscus forms part of the hernial
sac.3
Hanna Nilsson
1
Introduction
Groin hernia is a common disorder and its repair one of the most frequently
performed surgical procedures in the western world. The lifetime prevalence
of groin hernia repair has been estimated to be 27% in men and 3% in
women.4 More than 20 million hernia operations are performed each year
around the globe.5 Some 16 000 operations on patients above the age of 15
years are registered annually in the Swedish Hernia Register (SHR).6
Changes in groin hernia surgery over the last century have led to improved
results with low recurrence rates, and an increased concern for patient
satisfaction.7,8
The magnitude of repair makes groin hernia surgery an
important area of research, not only for the patient and his clinician, but also
for all authorities responsible for health economy and allocation of ever-
dwindling resources. Although often considered a minor procedure
performed as day-case surgery, serious events do occur after groin hernia
surgery, and registers play an important role in finding and analysing events
that are too rare to be identified by randomised controlled trials (RCT). The
aim of this thesis is to analyse serious events after groin hernia surgery, and
the risk for groin hernia operation after radical prostatectomy, using data
from large nationwide registers.
History, definition and prevalence of groin hernia
The word “hernia” descends from the Greek meaning “bud or shoot”.9 In
medical anatomy it is used to describe an abnormal protrusion of an organ
through a weakness in the wall of the cavity that normally withholds it.10
Groin hernia specifically occurs when an intra-abdominal organ or
peritoneum protrudes through a weakness in the abdominal wall in the area
above or below the inguinal ligament, giving rise to an inguinal or a femoral
hernia. Manuscripts from the ancient cultures of Mesopotamia and Egypt11
bear witness of groin hernia, ensuring us that the disorder is as old as
mankind itself, but exactly how common groin hernia is in men and women
is an area that remains unknown. Even today, the most cited hernia
prevalence study was performed in Jerusalem in the 1970s, where Abramson
Mortality and Morbidity after Groin Hernia Surgery
2
et al. found a lifetime prevalence rate of 48% in men aged 75 years and
older.12
Symptoms and indication for surgery
The symptoms of groin hernia vary from symptom-free to discomfort or pain.
If not operated, groin hernias can enlarge in size and cause mechanical and
hygienic hindrance, and in a worst case scenario, acute incarceration. In
countries with unmet demands for surgery, untreated groin hernias are often
associated with significant psychosocial stigmata,13
morbidity and even
mortality,14
and they also affect young individuals who are often the most
productive members of society.15,16
Surgery is the only cure for groin hernia and the aim of an operation is to
reduce symptoms and to prevent an acute complication such as incarceration,
strangulation or intestinal obstruction. A truss is less of an option in today’s
management of groin hernia.17
Watchful waiting is an acceptable short-term
alternative,18,19
but in the long run patients tend to be operated upon because
of the development of symptoms.20,21
Elderly patients should be considered
for operation since elective groin hernia surgery has been shown to be a low-
risk procedure even in elderly patients with known co-morbidity.22-24
Quality
of life, in terms of physical functioning and pain, improved significantly
after repair also in elderly.25
Groin hernia surgery is associated with
complications such as chronic pain, infection, seroma, but also with
intraoperative surgical or cardiovascular complications, and patients should
be adequately informed before entering the surgical theatre.
A patient with acute symptoms of incarcerated or strangulated hernia should
be operated on immediately since it is hard to differentiate between
strangulated and incarcerated groin hernia.26,27
Incarcerated and even
strangulated hernias are overlooked on the emergency ward because of
inadequate or lack of physical examination even though the patient has
symptoms consistent with bowel obstruction.28
For example, Hjaltson29
discovered that 13% (6/46) of emergency femoral hernias were found during
laparotomy initiated because of bowel obstruction. He also noticed that half
of patients treated for acute hernia were without inguinal pain but complained
of diffuse symptoms related to bowel obstruction. Whereas adhesions are the
most common cause of small bowel obstruction, groin hernia is the most
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3
common cause of strangulation in patients with small bowel obstruction.30
Bowel obstruction due to adhesions may resolve spontaneously, but
strangulation will not. Intestinal obstruction31
and necrosis followed by
resection are associated with high morbidity and mortality,32,33
and hence all
signs of bowel obstruction must lead to a physical examination for
inguinal/femoral hernia.
Figure 1. The importance of examining the patient and to fold aside the blanket while
doing so has to be emphasised. Femoral hernias are found below the inguinal ligament
and can be hard to find if not looked for systematically and thoroughly. Illustration by
Anna Erlandsson.
Mortality and Morbidity after Groin Hernia Surgery
4
In Sweden6 and in England
34 approximately 5% of all groin hernias are
operated on as an emergency cases associated with significantly increased
morbidity.24,35,36
However, only a fraction of these patients undergo
concomitant bowel resection because of strangulation.37
The risk for
strangulation is low in inguinal hernia.38
Gallegos et al.39
estimated the
cumulative probability of strangulation to be 2.8% for inguinal hernia in the
first 3 months after onset of symptoms. Femoral hernias, however, are over-
represented in emergency surgery26
with and without bowel resection, and
have been shown to have a high tendency to incarcerate and strangulate with
subsequently increased morbidity.33,36,39-43
For that reason femoral hernias are
usually considered for surgery even though symptoms are mild or absent.44
However, as with inguinal hernia it is not clear whether prophylactic elective
surgery prevents emergency surgery, since it has been shown that 53% of all
patients operated acutely for femoral hernia were unaware of their hernia
prior to operation.45
Gender differences
The prevalence of groin hernia, and hernia anatomy differ between genders.
The inguinal canal is created prenatally when the testicles in men and the
round ligaments in women descend from their intra-abdominal origins to the
scrotum/ labia majora.46
Prevalence of inguinal hernia surgery has two peaks,
one in early childhood and one in old age, and this applies to both genders.47
Congenital hernias in small children are indirect; caused by a failure of the
peritoneal sac, the processus vaginalis, to obliterate resulting in a patent
processus vaginalis (PPV).48
Child hernias are successfully repaired by
simple high ligation of the hernia sac,49
an operation associated with a high
recurrence rate in male adults.50,51
Hence, even though anatomically identical,
they are considered separately from the adult groin hernia52
and are not
further discussed in this thesis. More than 92% of all groin hernias reported
in the SHR6 are performed on men, and inguinal hernia is 13 times as
common in men than in women. However, the incidence of femoral hernia
has a female predominance of 1,8:1.53
This means that femoral hernia
comprises more than 20% of groin hernias in women compared to less than
2% in men. In contrast to inguinal hernia, femoral hernia is rare in children,
and the prevalence increases with age.47
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5
Groin anatomy
The abdominal wall, consisting of muscles, their aponeuroses and fascias,
maintain the integrity of the abdominal cavity. At the point where the
spermatic cord and femoral vessels leave the abdominal cavity in the groin, a
weakened area is created often referred to as the myopectineal orifice of
Fruchaud.54
It is quadrangular in shape and can be divided into three
triangles; lateral, medial and femoral.55
Direct hernias protrude through the
medial triangle, (Hesselbacks Triangle46
) bordered laterally by the inferior
epigastric vessels, medially by the rectus muscle, and inferiorly by the
inguinal ligament. Indirect hernias are located above the inguinal ligament
and lateral to the inferior epigastric vessels.56
Femoral hernias protrude in the
femoral canal that is 1-2 cm long and located below the inguinal ligament.46
The wide proximal end is called the femoral ring and lies medial to the
femoral vein, lateral to the lacunar ligament, anterior to posterior ramus of
the pubis and pectineus muscle, and posterior to the medial part of the
inguinal ligament. Studies have shown that even for experienced
examiners/surgeons, it is not possible to differentiate between an indirect and
a direct inguinal hernia by physical examination alone57
and it may even be
difficult to distinguish between a femoral and an inguinal hernia.58
The following three muscles are components of the abdominal wall and
important for the hernia surgeon. The external oblique muscle arises from
the lowest ribs. Caudally, its aponeurosis is condensed to the inguinal
ligament, passing from the anterior superior iliac spine (ASIS) to the pubic
tubercle. An opening in the aponeurosis just above the pubic tubercle creates
the triangular external inguinal ring through which the spermatic cord and the
round ligament run.
The internal oblique muscle arises from the lateral half of the inguinal
ligament and extends upwards medially. In the inguinal canal, the spermatic
cord passes adjacent or medial to this muscle, and the cord is coated with
muscle strips, the cremaster muscle, when passing alongside.
Mortality and Morbidity after Groin Hernia Surgery
6
Figure 2. Groin anatomy frontal view. The three potential groin hernia sites are
illustrated in relation to the inguinal ligament and inferior epigastric vessels. Illustration
by Anna Erlandsson.
The transverse abdominal muscle consists of more aponeurosis and much
less muscle than the two muscles mentioned above. The lower border of the
transverse abdominal aponeurosis is called “the arch.”56
Immediately deep
to the transverse abdominal muscle lies the transversalis fascia. Some
authors mean that the posterior wall below the arch consists of the
transversalis fascia alone creating, a weak area where direct herniation can
occur.52
Others mean that the posterior wall in all humans is made up of the
aponeuroses of the internal oblique muscle, the transverse abdominal
muscle, and transversalis fascia, although it varies in strength between
individuals.59
The internal ring of the inguinal canal has a shuttle mechanism first
described by Lytle in 1945.60
The U-shaped medial margin of the ring has
two limbs extending superiorly and laterally, attached to the transverse
muscle. Any increase in intra-abdominal pressure pushes the covering
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7
peritoneum forward to press the valvular ring more securely around the cord.
Also when coughing the columns of the ring are pulled together and the U is
draw upward, and laterally, hence “closing” the exit.56
Several attempts to classify groin hernia more precisely have been made
including a unified effort of the European Hernia Society (EHS)61-63
without
reaching a widely used consensus. In this thesis the classification is simple:
femoral, direct and indirect inguinal hernia.
Anatomy and prostatectomy
In 1996 Reagan et al64
published the first report indicating that the incidence
of groin hernia increased after Radical Retropubic Prostatectomy(RRP).
Since then a number of studies have confirmed an increased incidence of
groin hernia after prostatectomy compared to various control groups.65,66
Reported incidence rates vary from 6.7%-38.7%67
and variations might be
attributed to differences in observation time and methods used for identifying
groin hernia. Two large studies in Canada68,69
analysed incidence of groin
hernia repair after prostatectomy compared to patients receiving Radiation
Therapy (RT) or operated for other urologic diseases. They found that also
groin hernia repair increased significantly after prostatectomy, however they
could not differentiate between influence of open prostatectomy and
minimally invasive prostatectomy (MIRP). As mentioned earlier information
of incidence of groin hernia in the population, for men and women, is scarce
making it hard to interpret the reported incidence after prostatectomy.
The reasons for increased risk of hernia formation indicated in the above
studies are unknown. Stranne et al70
have argued for that it is the midline
incision that disrupts and destroy the transversalis fascia, important for the
integrity of the myopectinal orifice of Fruchaud. Others have noted an
association between postoperative anastomotic stricture71
and theorised that
an increase in intra-abdominal pressure, may cause hernia formation, in a
patent processus vaginalis. Fischer and Wants points out that the retractor in
RRP is placed near the area of the internal ring where it “deleteriously
stretches, strains, and deforms the groin”.72
The first and last arguments
would be in favor of MIRP where incisions and retractors are placed
differently. Some studies73
indicate that this is the case but further studies are
warranted.
Mortality and Morbidity after Groin Hernia Surgery
8
Methods of repair
Modern methods of groin hernia repair focus on reconstructing or
strengthening the posterior wall of the inguinal canal. Until the mid 20th
century this was mainly achieved by sutured repairs11
such as the Bassini74
or
later on, the Shouldice75
repair.
Open anterior repair
Eduardo Bassini, one of the most astonishing men in groin hernia history,
was born in 1844. After graduation in medicine at the age of 22, his
postgraduate training was with Billroth in Vienna, Langenbeck in Berlin,
Nussbaum in Munich and Lister in London.11
His interest in the inguinal
region is said to have come from a bayonet injury where he consequently
developed a faecal fistula in the right groin.76
This interest resulted in a new
surgical technique for groin hernias, and the method of Bassini first reported
in the 1890s was depicted step by step by Bassini’s pupil, Professor
Catterina, in an atlas named “The operation of Bassini.”74
It is not merely his
operative technique that made him into a master, but also the antiseptic
methods applied that included depilation, followed by cleansing of the
patient’s body with antiseptic solution. Intra-operatively he tested the repair
by lightening the anaesthetic of the patient who subsequently woke up and
vomited. Furthermore, a low infection rate of 4%, early ambulation, no truss,
and an extensive follow-up of 262 patients with a 2.7% recurrence rate gives
witness to the most thorough and knowledgeable of surgeons, even by
today’s standards.11
An essential part of his operation is the division of the
cremaster muscle and transversalis fascia, providing the surgeon with
complete insight of the internal opening and inspection of all potential hernia
sites. Reconstruction of the posterior wall is then accomplished by suturing
the threefold layer (internal oblique muscle, transverse abdominal muscle and
transversalis fascia) with single non-absorbable sutures to the inguinal
ligament.9,76
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9
Figure 3. Eduardo Bassini, 1844-1924, was an exceptional surgeon with recurrence rate
comparable of today. Preparations started the day before surgery where an assistant
overlooked by Bassini himself, shaved the patients’ whole body, apart from facial hair.
Then the bodies were cleansed with antiseptic solution and finally covered by linen
drenched in the same. When Bassini left the room a nurse stayed to make sure that the
patients did not move.11 Illustration by Anna Erlandsson
The reinforcement of the posterior wall of the inguinal canal made it
possible to cure inguinal hernias, but it was inadequate for femoral
hernias. In a modification known as the Mc Vay repair, the internal
oblique and transverse abdominal muscles are attached to Coopers
ligament, thereby narrowing or closing the femoral canal. 77
This is made
possible through a relaxing incision in the anterior rectus sheath whereby
the various components of the abdominal wall are displaced laterally and
inferiorly.78
Mortality and Morbidity after Groin Hernia Surgery
10
Earl Shouldice, in Toronto, also stressed that all potential hernia sites
must be assessed and repaired if necessary.79
A missed hernia was
frowned upon as a cardinal mistake. Like Bassini he emphasised the
importance of the transversalis fascia in reconstructing the posterior wall
of the inguinal canal. Shouldice repaired the posterior wall with four
layers and a running steel-wire suture. Later Kux et al80
showed equally
good results using a modification with a two-layer technique.80
Apart
from using steel-wire and suturing four separate layers, the similarities
between the Bassini and the Shouldice repair are evident.9
Unique for the reports describing the two techniques is the thorough
follow-up of patients. More than a century before the SHR, Bassini
reported a 2.7% (7/262) recurrence rate in a four-year follow-up.81
In
1953 Shouldice presented a 0.8% recurrence rate after ten years82
that has
stayed below 1% in the hands of the surgeons at the Shouldice
Clinic.75,83,84
This technique, reproducible by other surgeons, suggests the
Shouldice repair to be the “gold standard” of sutured repair.17,85,86
The tension-free hernioplasty
The use of synthetic mesh in groin hernia markedly reduces the risk for
hernia recurrence regardless of placement method, compared to sutured
repair.17,87
Already in the late 50’s after careful in vitro studies, Usher88,89
showed how to use polypropylene monofilament mesh in groin hernia
surgery to avoid tension in the tissue. However, it was not until 198690
when
Irving Lichtenstein published a report of a tension-free hernioplasty, that the
mesh technique was used in a larger scale. Under local anaesthesia, a floppy
net was inserted, covering the defect in the transversalis fascia thereby
reconstructing the posterior wall of the inguinal canal without tension.91
Lichtenstein questioned why one should strive to “reconstruct normal
anatomy when the mere presence of a hernia has already attested to the
deficiency” of the inguinal floor.52
The repair known as Lichtenstein repair
was a giant leap forward towards a lower recurrence rate. In 2005, it was the
preferred method in high income countries where 96% of British, 99% of
Japanese and 86% of American surgeons practiced it.92
In Sweden hernia
surgery changed dramatically - from a majority of repair performed as
sutured repair in 1992 to a majority of repair performed as Lichtenstein repair
four years later (Figure 4). A similar trend was reported in other countries
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11
such as Denmark5 and the Netherlands.
93 Today the Lichtenstein repair
represents more than 70% of groin hernia repair in Sweden6 and has the best
results in the hands of Swedish surgeons regarding reoperation rate.94
Modifications concerning the anchoring of the mesh with glue or self-fixating
mesh have yielded similar results in terms of postoperative pain95
and
recurrence rate.96
Lightweight mesh has better results than heavyweight in
terms of postoperative pain, with similar recurrence rates,97
and in fact, even
sterilised mosquito-net can be used with excellent results98,99
in safe100
hernia
surgery. Plug repairs, with equally low recurrence rates, have been associated
with complications (especially pain) maybe because of its three-dimensional
shape.101
Methods of repair in men, 1992-2012
Figure 4. Choice of operative technique in 219 047 repair registered in men, 1992-2012.
Dramatic changes occurred during the 1990’s when Lichtenstein repair was introduced.
Mortality and Morbidity after Groin Hernia Surgery
12
Preperitoneal repair
In the groin region, behind the transversalis fascia and anterior to the
peritoneum and the abdominal cavity, lies the preperitoneal space often
referred to as the space of Bogros.56
Many surgeons have been involved in
the continuous refinement of the preperitoneal technique. In the 1920s
Cheatle entered the space of Bogros via a midline incision. Stoppa described
his giant (bilateral) prosthetic reinforcement of the visceral sac (GPRVS)102
covering all hernia sites. Read, placed the mesh preperitoneally via an
inguinal incision,103
nowadays referred to as the Trans-Inguinal Pre-
Peritoneal technique, (TIPP). 104
Nyhus popularised this technique by using a
unilateral paramedian incision, initially by suturing the transverse muscle to
the iliopubic tract105
and later by using mesh106
for reconstruction of the
posterior wall of the inguinal canal. Today, the posterior approach
(endoscopic or open) has been recommended for women and in recurrent
hernia surgery where the primary operation has been performed with an
anterior approach.17
There are three important advantages with the preperitoneal approach: it
avoids the distortion of the inguinal canal leaving intact nerves and testicular
blood supply; it permits inspection and potential cure for all hernia sites in
the groin; and if performed as open surgery it allows for easy access to the
abdominal cavity if necessary.
Laparoscopic repair
The first laparoscopic hernia repair was reported in 1982107
and the technique
introduced a “novel” view of the well-known preperitoneal space where the
myopectineal orifice is easily visualised and covered with a mesh, a potential
solution for all hernia sites. In the Trans-Abdominal Pre-Peritoneal
approach108
(TAPP) the pre-peritoneal space is reached via the abdomen
where the peritoneum is incised and folded aside during the operation. In the
Totally Extra-Peritoneal approach109
(TEP) the preperitoneal space is reached
directly without entering the abdominal cavity, thereby minimising the risk
for abdominal visceral complications. According to some studies
laparoscopic and open repairs result in similar recurrence rates110,17
whereas
others111,112
show a higher recurrence rate after laparoscopic surgery
compared to Lichtenstein. A meta-analysis performed by O’Reilly et al. 113
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13
found a significant increase in the risk for recurrence with the TEP compared
to the open technique, whereas the TAPP was equivalent to open mesh repair
regarding recurrence, but had a higher perioperative morbidity rate. The
laparoscopic technique requires general anesthesia for most patients, which is
a disadvantage, but it is easily performed as day-case surgery. Compared to
Lichtenstein, the laparoscopic technique has higher long-term costs114,115
and
a longer learning curve116,117
whereas, chronic pain after five years is higher
for the open technique, albeit low for both.118
If the technique is available,
EHS guidelines17
recommend it for bilateral hernia, for recurrent surgery
when the primary operation has been performed with an anterior approach,
and for women.
Method of operation in women, 1992-2012
Figure 5. Trend of operative technique in 19 239 repair registered in women in SHR,
1992-2012. As in men Lichtenstein technique increased in mid 1990s but has since
dropped in number in favor of preperitoneal technique.
Mortality and Morbidity after Groin Hernia Surgery
14
Methods of anaesthesia
Groin hernia surgery can be performed using the three principal forms of
anaesthesia.
1. General anaesthesia
2. Regional anaesthesia
3. Local anaesthesia
Method of anaesthesia registered in SHR, 1992-2012
Figure 6. Method of anesthesia in men registered in SHR, 1992-2012.The use of spinal or
regional anaesthesia has decreased markedly below 10% while use of local anaesthesia
increased during the 1990’s. However, local anaesthesia is not used for more than 20% of
operations registered.
Local anaesthesia has been used at the Shouldice clinic in 95% of patients
for more than 50 years.83,119
Lichtenstein also used local anaesthesia for
tension-free repair, and tried to explode the myth that “the use of local
anaesthesia for inguinal herniorrhaphy requires special expertise and
increases the length and difficulty of the operation.”52
The technique120
is
simple but requires practice.121
Three large randomised controlled trials
comparing local, regional and general anaesthesia provided robust evidence
showing that local anaesthesia is time-saving, cost-effective, and that
surgeons are able to operate as day-case surgery with greater patient
satisfaction.122-126
Regional anaesthesia has been associated with an increased
morbidity rate127
compared to local and general anaesthesia, especially
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15
cardiovascular complications128
probably due to induced bradycardia and
cardiac arrest.129
Local anaesthesia also has the advantage of a conscious patient able to cough
to demonstrate the hernia intraoperatively, if necessary. Despite the
advantages of local anaesthesia, surgeons only use the technique in 17% of
operations performed in Sweden. However, the variation among hospitals is
great and one unit uses local anaesthesia for 80 % of its patients with
excellent results. As for surgery, the panorama of anaesthesia has changed
dramatically over the past 20 years (Figure 6). In 1992, 75% of operations
were performed under regional anaesthesia; in 2012 this was less than 10 %.
EHS guidelines recommend local anaesthesia for open repair and do not
recommend regional anaesthesia at all.17
Complications of groin hernia repair
Complications commonly associated with groin hernia repair are haematoma,
seroma, pain and infection. A meticulous, nerve-saving dissection technique
and careful haemostasis is therefore important.130
Testicular atrophy is a
feared, but rare, complication caused either by impairment of the venous flow
or hypoxic reaction secondary to obliteration of the blood supply to the
testicle.131
In the SHR 8% (11,995/ 150,514) of patients had one or more
complications registered within 30 days of surgery. Preperitoneal techniques,
open as well as laparoscopic, were associated with an increased complication
risk with odds ratios of 1.35(1.24-1.47) and 1.31 (1.15-1.49), respectively.132
Bleeding, arterial or venous, may occur in all groin hernia repairs, and from
all vessels in the surgical field.131
However, three vessels should be especially
feared during operation; the pubic branch of the obturator artery, sometimes
referred to as the corona mortis; the deep inferior epigastric vessels; and the
external iliac artery and vein.130
Laparoscopic repair has been associated with
more serious complications than the other methods.110,111,112
Complications are largely associated with emergency operations.4,32,35,133
Other risk factors known are recurrent hernias,134
sliding hernias,135
and
bilateral136
hernias.
Mortality and Morbidity after Groin Hernia Surgery
16
Swedish Hernia Register
In 1992 the Swedish Hernia Register started with 8 aligned hospitals. It is a
national quality register aimed to “ describe and analyse hernia surgery and
stimulate improvements at the participating units.”137
Today, more than 20
years later, almost all groin hernia operations performed in Sweden are
registered in the SHR, providing a database of more than 250 000
prospectively registered operations. More than 40 publications and 9 theses
have been based upon SHR data.
With permission to use personal identification numbers, a number unique for
each Swedish citizen,138
patients are followed prospectively from operation
until reoperation for recurrence or death, regardless of where in the country
the reoperation is performed. Information is registered on-line at the time of
the operation. Follow up is not required but the participating units have an
obligation to report all complications within 30 days of surgery that comes to
their knowledge. Data are processed annually, and feed-back is available for
each participating unit, where outcomes obtained at a specific unit are
compared with results obtained at all participating units combined. Over-all
information is obtainable on the web for all interested to read. Five
independent evaluators randomly visit 10% of the aligned units each year and
check the validity of the data registered in the SHR, as well as check for
operations not registered. The register has been found to include some 98%
of all operations eligible. 139
Already in 1998 one could see that the participation in SHR resulted in better
care for the patients at the aligned hospitals. A comparison between two
hospital cohorts one participating in the SHR from the start (1992) and the
other joining in 1995 indicated that both quality and cost-effectiveness
improved with register participation.140-142
Today, it is evident that the quality of groin hernia surgery offered to patients
in Sweden has improved. The proportion of recurrent hernias (of all hernias
operated) decreased from 17% in 1995 to 9% in 2012. Day-case surgery has
increased from below 35% to 80%, and the risk for re-operation for
recurrence has decreased markedly. (Figure 7)
Hanna Nilsson
17
Cumulative incidence of reoperation vs. year of treatment
Figure 7. Cumulative incidence of reoperation for hernia repairs registered in SHR for
three time-periods. Between 1992 and 1998 the cumulative reoperation rate for
recurrence was nearly 3% in two years follow up. Little more than a decade later the
cumulative incidence of reoperation has decreased to approximately 1.5%.
Mortality and Morbidity after Groin Hernia Surgery
18
Register studies
Register studies are observational, studying the effectiveness in routine care,
in contrast to experimental trials that are investigational, studying the efficacy
or the results obtained in expert hands when correctly applied to appropriate
patients.143
Widely recognised as the gold standard to evaluate
pharmacological interventions,144
randomised controlled trials (RCT) pose
specific problems in surgical research.145,146
In this respect register studies
can complement RCT’s by revealing the impact different treatments have in
wider practice.147
In Sweden there are mandatory registers and national quality registers.
Examples of mandatory registers, initiated and controlled by the National
Board of Health and Welfare, are the Swedish Cancer Register, the Cause of
Death Register and the Swedish National Patient Register (NPR. 148
National
quality registers are non-mandatory for hospital/units and aim at improving
the quality of care for patients with specific diseases/interventions included in
the registers. Some features are important for all registers.
Inclusion is regulated by law for mandatory registers. Quality registers, on
the other hand, must appeal to participating units. The SHR, for example,
offers its participants an opportunity to improve their outcome by giving
feedback in an annual report.
Validity is crucial for register studies, and validation is a complicated task
requiring cross-checking. A register with incorrect or missed data is of
limited use.
The ability to trace patients. All Sweden citizens have a unique personal
identification number138
making the patient traceable in the healthcare
system, and enables registers to merge with one another to broaden fields of
research. The fruit of one such merger of 11 nationwide registers is called
PCBaSe. This database has made it possible to investigate clinically relevant
issues such as adverse outcome after prostatic cancer treatment; implication
of co-morbidity,149,150
psychiatric health and suicide risk,151,152
risk for
cardiovascular complications,153,154
healthcare provided contra social
group,155
and watchful waiting or not.156,157
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19
Extrapolation to the population. As stated above the external validity for
nationwide register data is high. Register studies are epidemiological and in
contrast to RCTs without inclusion- or exclusion criteria i. e. unselective
data.
Changes over time. In RCTs, it is not possible to have a follow-up that
stretches for more than a few years because of the high cost. A register study,
however, is an excellent tool for observing changes over long periods of time.
Late re-operation for recurrence is one endpoint that cannot easily be
examined by RCTs, whereas it is readily investigated by register studies.
Short-term recurrence rates can accurately be determined in RCTs using both
physical and radiologic examinations because of the limited number of
patients. Without the use of questionnaires, recurrence rates cannot be
examined in the SHR, which is why register studies are forced to use the
endpoint re-operation for recurrence.
The importance of a control group. In the beginning of the 2000s, the
reputation of observational studies became tainted when they suggested
negative associations between the use of hormone replacement therapy
(HRT) and a risk for cardiovascular events. The authors of one of these
observational studies did indeed reflect on this when writing: “the
associations described may reflect differences between hormone users and
non-users rather than the effect of hormones themselves.”158
According to a
RCT, no such effect could be ascribed to HRT, while other harmful effects
were noted instead.159
When investigating for example a risk of a
cardiovascular event the risk should be put in the context of corresponding
risks in the background population. As depicted in the example above, choice
of comparison group is more critical in observational studies than in
interventional studies where patients often are randomly allocated to equalise
the groups being compared.
Registers are powerful tools when studying rare adverse events. Thomas
Kuhn, an American professor and author of “The structure of scientific
revolution160
” described the scientific community living in different
paradigms each and every one by its own “truths” and “normal knowledge”.
Anomalies within this “normal science” are too small (or rare) for the
individual scientist to consider them worth exploring. However, eventually
Mortality and Morbidity after Groin Hernia Surgery
20
and collectively, anomalies cannot be ignored causing a model drift, model
crisis and eventually a model revolution ending in a paradigm shift where
new “normal knowledge is formed”. An example from the SHR’s history is
used to illustrate this issue:
Cumulative risk of reoperation in men
Figure 8. Cumulative risk of reoperation vs. method of repair in men, 1992-2012.
Compared to the Lichtenstein technique all other methods of repair are associated with
increased risk of reoperation.
Hanna Nilsson
21
The Lichtenstein technique was associated with a low recurrence rate (Figure
8) and reproducible results, initially assumed (normal knowledge) to give
equally good results regardless of gender. Hence, women were treated with a
method acknowledged to be excellent in men. After a decade more than 6 895
groin hernia repairs in women had been registered in the SHR.161
When men
and women were analysed separately, it became clear that the technique
proven best for men had inferior results in women. (Figure 9)
Cumulative risk of reoperation in women, 1992-2012
Figure 9. Cumulative risk of reoperation in women 1992-2012. The Lichtenstein
technique is set as reference. A 2% reoperation for recurrence rate is reached within a
year for the Lichtenstein repair whereas the preperitoneal laparoscopic technique has
significantly lower reoperation for recurrence rate.
Mortality and Morbidity after Groin Hernia Surgery
22
In hindsight this should have be suspected from the information known at
that time. The Shouldice hospital had noted that more than half of all patients
operated for femoral hernia were reoperations. 79
Mikkelsen et al.162
noted a
fifteen-fold increase in incidence of femoral hernias in reoperations for
recurrence compared with the spontaneous incidence. In the SHR, 42% of
women re-operated for recurrence, had a femoral hernia whereas the
corresponding figure for men was 5%.161
Oddly enough, the exact same
figures were reported by the Danish Hernia Register; 42% and 5%.163
One
conclusion from both studies was that femoral hernias are overlooked at
operations for inguinal hernias. Hence, the internal orifices of both inguinal
and femoral hernias should be explored in groin hernia surgery, in women.
As femoral hernias are relatively more common in women, they should be
repaired with a technique that allows easy visualisation of the sites for both
inguinal and femoral hernias i.e. with a preperitoneal technique - open or
laparoscopic. These techniques were also found superior in women when re-
operation was set as a quality endpoint.161
The figures above show
cumulative re-operation rates with respect to method of repair for men and
women.
Hanna Nilsson
23
Aims of the thesis
I. To investigate the mortality after groin hernia surgery, adjusted for
mortality in the background population.
II. To investigate symptoms, cause of death, and treatment of patients
who died within 30 days after groin hernia operation.
III. To investigate the incidence of groin hernia surgery after
prostatectomy and radiation therapy for prostate cancer compared to
a control population.
IV. To investigate severe postoperative adverse events within 30 days
after groin hernia repair.
Mortality and Morbidity after Groin Hernia Surgery
24
Methodological considerations
The register studies below are hypothesis-creating rather than hypothesis-
driven. The aims of the studies are to depict and analyse reality. Below
follows a description of registers, other than the SHR, used in the studies:
The Cause of Death Register: started in 1961. For all Swedish citizens
dying in or outside Sweden, date and cause of death is registered according to
ICD-9, or ICD-10 reference codes. The under-reporting is low (less than
0.4% in 1986).164
The Swedish Cancer Register includes all patients in Sweden with a
diagnosis of cancer. It is regulated by law that cancer diagnoses must be
reported both by the clinician and the pathologist.165
Approximately 60 000
cases of cancer are reported each year in Sweden.
The Swedish National Patient Register (NPR) also called Hospital
Discharge Register collects information on in-patient care, including surgical
procedures and discharge diagnoses according to ICD-9 or ICD-10 reference
codes.148
It started in 1964 and received complete coverage in 1989. From
2001, outpatient visits such as day-case surgery are included. The
completeness of this register has been shown to be high, and in 2007 drop-
outs not registered in the register were estimated to be less than 1%.166
The National Prostate Cancer Register (NPCR) was established in 1996
and includes all patients with the diagnosis prostate cancer (PCa) covering
more than 96% of all PC cases registered in the Swedish Cancer Register.167
The validity of primary treatment registered in the NPCR is above 90%
correct for curative treatment and surveillance, and more than 95% correct
for endocrine treatment.168
PCBaSe 2.0 is a database with information from a merger of the NPCR and
eleven other Swedish nationwide registers.168,169
Information in the PCBaSe
2.0 runs from 1998-2008 and it is based upon 119,777 patients registered in
the NPCR. Unique for this database is their control-group. For every man
Hanna Nilsson
25
with PCa included, two or five (depending on year of inclusion) men without
a diagnosis of PCa were randomly selected, matched for age and place of
residence. The control-group consists of more than 600,000 men.
Paper I
Paper I is an observational cohort study with a comparison group. The SHR
was merged with the Cause of Death Register to find patient mortality within
30 days of groin hernia surgery. The mortality rate was compared with that of
the Swedish background population using a standardised mortality ratio
(SMR) (see statistical considerations). The SMR was analysed for gender,
method of repair, anaesthesia, groin anatomy, age, ASA-score and mode of
admission, among patients operated for groin hernia.
Paper II
Paper II is a descriptive study, analysing the care given to patients who died
within 30 days after hernia surgery. In order to find out why patients in Paper
I had died within 30 days of surgery medical records of deceased patients
were examined. A request was sent to all participating units for the medical
records of each and every one of the deceased patients. Data in the SHR are
collected prospectively for each operation. However, patient files were
retrieved retrospectively. Parameters looked for in the medical records were:
symptoms at admission; examination in the emergency department;
radiologic examination; and time from hospital admission to surgery.
Paper III
Paper III is an observational, retrospective, cohort study based on data from
the PCBaSe 2.0. The incidence of groin hernia repair was analysed for men
with prostate cancer treated with radiation therapy and prostatectomy (open
as well as minimally invasive), and compared with a control group of more
than 100,000 men free of prostate cancer matched for area of residence and
age. The Cox proportional hazard model was used to calculate hazards ratios
(HR).
Mortality and Morbidity after Groin Hernia Surgery
26
Paper IV
Paper IV is an observational cohort study where SHR was merged with the
NPR to find severe complications, both medical and surgical, within 30 days
after groin hernia surgery. Intraoperative complications were found in SHR,
and ICD and reoperation codes were found in NPR. Odds ratios were
calculated using multivariate logistic regression analyses to compare the risk
for cardiovascular or adverse surgical events. Variables of interest were
method of operation and anaesthesia, hernia anatomy, age, ASA-score, and
mode of admission. A 95% confidence interval was used to estimate the
precision of OR.170
Hanna Nilsson
27
Statistical considerations
Standardised Mortality Ratio (SMR) was used in paper I to relate the
mortality rate of patients to that of the background population. The SMR
equals the observed number of deaths in the study group divided by the
expected number of deaths in a Swedish population with same composition
as the study group. An SMR above 1 is equivalent to an increased risk
compared to that of the background population and an SMR below 1 with a
decreased risk.
Odds Ratio (OR): a comparison of two odds: the odds of the event occurring
in one group divided by the odds of the event occurring in the other group. It
does not equal relative risk (RR) when the proportion with the outcome is
greater than 5-10%, meaning that the term has little clinical relevance or
meaning with higher incidence rates.171
If the OR is 1 the RR is 1. In all other
circumstances they will differ.
Hazards Ratio (HR): The hazard rate is the probability that if the event has
not already occurred that it will occur in the next time interval divided by the
length of that interval.172
The assumption in proportional hazard model for
survival analysis is that the hazard in one group is a constant proportion of
the hazard in the other group. This proportion is Hazards Ratio.
Translated to fit paper III it means: the odds that the time to hernia operation
is less for a patient in the treatment group than for a patient in the control
group.
Relative Risk (RR): or risk ratio is the risk of outcome in the exposed group
divided by the risk of outcome in the unexposed. If the risk of the outcome is
the same in both groups then the RR is 1.0 indicating no association between
exposure and outcome.171
Mortality and Morbidity after Groin Hernia Surgery
28
Results
Paper I
Between the years 1992 and 2004, 292 out of 103,710 patients died within 30
days after surgery. Table 1 shows the SMRs versus groin anatomy, gender,
mode of admission, and bowel resection. Red numbers indicate a
significantly increased risk compared to the background population, and
green numbers a significantly decreased risk. An emergency operation was
associated with an increased risk especially in women, as was femoral hernia
with a SMR of 6.8 (4.3-10.3) in men and 7.2(4.8-10.3) in women.
Table 1. SMR in relation to anatomy, gender and mode of admission
No op. Observed deaths Expected deaths SMR 95% CI
Anatomy
Inguinal 100,816 241 175 1.38 1.2 – 1.6
Femoral 2,894 51 7 7.01 5.2 – 9.2
Gender
Men 95,692 235 167.69 1.40 1.2-1.6
Women 8,018 57 13.67 4.17 3.2-5.4
Elective surgery
No bowel resection 97,231 104 157 0.66 0.5 - 0.8
Bowel resection 202 3 0 6.98 1.4 - 20.4
Total 97,433 107 157 0.68 0.6 - 0.8
Emergency surgery
No bowel resection 5,783 123 24 4.95 4.1 - 5.9
Bowel resection 494 62 3 21.53 16.5 – 27.6
Total 6,277 185 27 6.70 5.8 – 7.7
Hanna Nilsson
29
Paper II
242 medical records (of 292 deceased patients) were retrieved and
scrutinised. One quarter (38/152) of 152 patients operated acutely had a
femoral hernia. In 70% (107/152) of emergency operations, patients were
admitted because of symptoms of bowel obstruction with or without a
palpable hernia.
Women were less likely to be examined for groin hernia in the emergency
ward, 61% vs. 78% (P=0.04), even though they had symptoms indicating
bowel obstruction. If admitted for bowel obstruction without a correct
diagnosis, 30% were operated within 24 hours compared to 82% if the
diagnosis of groin hernia was determined in the emergency ward.
Table 2. Diagnosis on the emergency department vs. time to surgery
Bowel obstruction without known hernia
Bowel obstruction with known hernia
Op within 24 h 30% 82%
Op after 24 h 70% 18%
Mortality and Morbidity after Groin Hernia Surgery
30
Paper III
26,608 men with PCa treated with open prostatectomy (RRP), minimally
invasive prostatectomy (MIRP) or radiation therapy (RT) were included in
the study together with a control group of 105,422 men without PCa. After
six years approximately 4% of the control population had been subjected to
groin hernia repair in contrast to 14% of patients operated with open
prostatectomy. A small but significant difference was seen between open and
minimally invasive surgery, where 11 % were operated after 6 years. 8% of
patients with prostate cancer who received radiation therapy had been
operated for hernia by 6 year. With the control group as reference Hazards
ratios were 3.95(3.70-4.21) for open prostatectomy 3.37(2.95-4.21) for
minimally invasive prostatectomy and 1.84(1.66-2.04) for patients treated
with radiation therapy.
As seen in table 3, it was the proportion indirect hernias that increased after
open prostatectomy.
Table 3. Hernia anatomy as registered in SHR in patients treated for PCa and controls
Femoral(%) Combined(%) Indirect(%) Direct(%) Other(%)
Control 1 10 53 36 0.4 RT 1 8 65 26 1 RRP 0.4 6 77 16 1 MIRP 0.4 10 66 23 0
Hanna Nilsson
31
Paper IV
Accoring to NPR, 612 out of 143,042 patients, 12,001 (8%) women and
131,041 men (92%), suffered from at least one cardiovascular event within
30 days after surgery, and 295 groin hernia repairs were followed by a
serious surgical event detected either by discharge diagnosis or by re-
operation code. According to SHR, in 815 repair one or more intraoperative
complications occurred. Male gender was associated with a significantly
increased risk for cardiovascular events compared to women. Age above 60
years, ASA-score above 2, emergency operation, and regional anaesthesia
was associated with increased risk for cardiovascular complications. All
method of operation apart from open anterior mesh repair were associated
with an increased risk either for intraoperative complication noted in SHR or
severe surgical complication detected by registered codes in NPR. In addition
bilateral hernia, sliding hernia, and recurrent hernias were associated with
increased risk for both intra-operative complication and severe surgical
complication.
Table 4. Odds ratio for severe surgical complications recorded in NPR vs. method of operation
Men Women
Odds ratio p-value 95%CI Odds ratio p-value 95%CI
Method of op
Open anterior 1(Reference) 1(Reference)
Laparoscopy 0.9 0.626 0.5-1.6 1.0 0.980 0.3-3.7
Open posterior 2.4 0.007 1.3-4.4 2.3 0.089 0.9-5.8
Suture repair 2.2 <0.001 1.4-3.5 0.5 0.318 0.1-2.1
”Other” repair 2.2 0.041 1.0-4.7 2.3 0.067 1.0-5.5
Mortality and Morbidity after Groin Hernia Surgery
32
Conclusion
Elective groin hernia repair is a low risk procedure even in elderly
Emergency hernia operation is associated with considerable
mortality and morbidity
In groin hernia repair, women have a higher mortality risk than
men due to a greater risk for emergency procedure irrespective of
hernia anatomy and a greater proportion of femoral hernia.
A physical examination for groin hernia in patients with bowel
obstruction shortens time to operation
Regional anaesthesia is associated with an increase in
cardiovascular morbidity compared with local anaesthesia
Emergency hernia, sliding hernia, bilateral hernia and recurrent
hernias were associated with an increased risk of surgical
complications.
Groin hernia repair is significantly increased in patients treated
with open prostatectomy, minimally invasive prostatectomy as
well as after radiation therapy for PCa, compared to a control
cohort.
Hanna Nilsson
33
General Discussion
Great improvement in hernia repair in Sweden has occurred since the onset of
the Swedish Hernia Register in 1992, to the benefit of groin hernia patients.
The nationwide recurrence rate has dropped below 2% in two years, day-case
surgery is well-established, and the proportion of operations performed under
local anaesthesia has increased, albeit still low. This thesis also demonstrates
that convergence of registers is feasible, informative and useful when
performing studies on rare events.
Strengths and weaknesses
The registers used in the thesis have all been shown to have a high validity,
crucial for register studies, and they are also nationwide meaning that no
class, group, or patient category is excluded. Hence, the results obtained are
applicable to patients in the waiting room or on the emergency ward in any
hospital or unit. Observational register studies, such as those presented in this
thesis, are important complements to randomised controlled trials, where
experts exert their skill under optimal conditions.173
One important strength of register studies is the great number of patients and
operations registered, making it possible to find and analyse rare events such
as mortality and severe adverse events. The number of patients needed to
address these rare outcomes in a RCT is too large to be feasible.
The exceptional PCBaSe database is a golden example of convergence of
registers. The strength of Paper III, besides the vast number of operations, is
the unique control group created in PCBaSe, making it possible to relate the
incidence of groin hernia repair to the background population. In the control
group a mere 4% had been operated within 5 years, a figure which concurs
with findings from the Danish register where 4.14% CI 4.0–4.29% of all
males aged 75–80 years in Denmark were operated for an inguinal hernia at
least once during a 4-year period.47
Mortality and Morbidity after Groin Hernia Surgery
34
Operation for groin hernia or reoperation for recurrence are blunt endpoints
since we know that the incidence of groin hernia exceeds that of groin hernia
surgery.174
In Paper I, selection bias may be suspected since electively
operated patients have a lower mortality rate than the background population,
suggesting that surgeons tend to select healthy patients for hernia surgery. In
Paper III, a potential detection bias is that all patients with prostate cancer
visit a doctor on a regular basis in contrast to controls.
An obvious weakness in register studies is the lack of personal information of
each patient. However, it is possible to combine register studies with
complementary questionnaires175
or with analyses of patient files as in Paper
II.
Main findings
In Paper I it was found that mortality after elective groin hernia repair is low,
even lower than for the background population. Together with other
studies22,25
this supports the decision to operate an elderly man or women
suffering from groin hernia electively, and even suggests that indications for
patients with co-morbidity should be widened. Emergency hernia surgery, on
the other hand, is known to be associated with increased mortality and
morbidity, a truth confirmed in Papers I and IV.
For the first time in a larger study it was concluded that patients operated on
because of bilateral hernias have a significantly higher risk of having a severe
adverse event and intraoperative complications. This must considered when
planning for operation in individuals with bilateral hernias. Risk for
intraoperative or severe complications were also influences by the method of
repair chosen and this must also be taken into account when planning the
operation for the individual patient at your clinic.
Women have a higher mortality risk than men because of a higher proportion
of femoral hernias and a higher fraction of emergency operations regardless
of hernia anatomy. According to the medical files, women with incarcerated
groin hernias were at a higher risk than men for not having a correct
diagnosis on the emergency department. Kjaergaard et al.28
analysed patient
deaths in the Danish Hernia Register, and also observed that 41% of patients
lacked an examination for groin hernia with subsequent delayed diagnosis
Hanna Nilsson
35
and treatment. Also, McGugan et al found that 59% of femoral hernia
operation that led to death was performed outside office-hours and often by
junior staff.176
Overall mortality after femoral hernia surgery in women in
their study was 3.1 % (37/1184). The awareness of the increased
morbidity/mortality in this group of patients hopefully results in less time to
surgery, better preoperative care, and consultation of more experienced
surgeon and/ or anaesthesiologist when needed.
The three-fold elevated risk for having a groin hernia operation after open as
well as minimally invasive surgery for prostate cancer has implications both
for the urologist, the surgeon and the health economist. In contrast to our
findings, minimally invasive surgery has previously been associated with a
lower risk for groin hernia than open radical prostatectomy.73
However, a
recent study by Carlsson et al. showed that minimally invasive surgery was
associated with a greater risk for any hernia repair, and specifically for
incisional hernia repair, compared to open prostatectomy.177
Since
prostatectomies are increasing in number, the number of hernias will
increase, and cooperation between urologists and surgeons is required, to
meet the increased risk for both incisional and groin hernia repair
Mortality and Morbidity after Groin Hernia Surgery
36
Future perspectives
Prevalence studies on groin hernia in the normal population, especially in
women, are needed in order to improve interpretation of results from register
studies and to improve our advice to patients on whether to operate their
hernia or not. With the convergence of registers we can stretch the use of
register studies further to investigate parameters such as the socio-economic
impact on groin hernia mortality and morbidity. A famous hernia surgeon
wrote “Nothing so prevents the occurrence of complications as one´s
awareness and fear of them.”131
In order to decrease the mortality and
morbidity seen after emergency hernia operations and operations for femoral
hernia repair, recurrent hernia repair, bilateral hernia repair and female groin
hernia repair in general, it may be appropriate for two surgeons to attend such
operations. My sincere hope is that the present excess mortality in women
after (emergency) groin hernia repair will decrease because of our better
awareness of associated risks. I also believe that this should be controlled
with follow-up studies as outlined in Paper I.
Hanna Nilsson
37
Sammanfattning på svenska
Ljumskbråck är ett vanligt tillstånd och årligen genomförs 20 miljoner
operationer värden över. Svenskt Bråckregister (SBR) startades 1992 och
inkluderar idag mer än 95 % av alla operationer utförda på män och kvinnor
över 15 år i Sverige. Avsikten med registret var att kartlägga
ljumskbråckskirurgin och förbättra dess kvalitet, och antalet omoperationer
har sedan dess minskat stadigt. Allvarliga komplikationer i samband med
ljumskbråckskirurgi är få men det stora antalet operationer gör dem ändock
viktiga för patienten, kirurgen och för hälsoekonomin som styr våra resurser.
Syftet med avhandlingen är att utvidga registrets användningsområde genom
att samköra SBR med andra nationella register för att studera ovanliga
händelser och allvarliga komplikationer efter ljumskbråckskirurgi.
Delarbete I
Risken att avlida inom 30 dagar efter ljumskbråckskirurgi analyserades
genom att samköra SBR med dödsregistret. Eftersom ljumskbråck i hög
uträckning drabbar den äldre befolkningen jämfördes dödligheten efter
ljumskbråckskirurgi med den hos normalbefolkning, kontrollerat för ålder
och kön. Planerade operationer medförde ingen ökad dödlighet utöver den
förväntade även vid hög ålder. Däremot var dödligheten efter akut operation
kraftigt ökad, särskilt vid samtidig tarmresektion. Kvinnor som genomgick
ljumskbråckskirurgi hade en betydande överdödlighet jämfört med män,
vilket tolkades bero på den stora andelen kvinnor som opereras akut.
Delarbete II
För att ta reda på varför patienterna avled granskades 242 av 292 journaler
över patienter som avlidit inom 30 dagar efter ljumskbråckoperation. Ett
inklämt ljumskbråck ger symtom som vid tarmvred med magsmärta,
kräkning och utebliven avföring. Trots detta ljumskbråcksundersöktes bara
61 % av kvinnor, med tarmvredssymtom jämfört med 78 % av männen. De
patienter där läkaren inte ställde diagnosen inklämt ljumskbråck på
akutmottagningen utsattes i högre utsträckning för (onödig) radiologisk
Mortality and Morbidity after Groin Hernia Surgery
38
undersökning och opererades betydligt senare jämfört med patienter som
erhöll diagnosen ljumskbråck på akutmottagningen. Ett viktigt budskap från
studien är riktat till läkaren på akutmottagningen. Undersök ljumskarna hos
alla som kommer med symtom på tarmvred!
Delarbete III
Studier har visat på en ökad risk att drabbas av ljumskbråck efter
prostatacanceroperation. För att med större säkerhet kunna besvara frågan
samkördes SBR med Nationellt ProstataCancer Register. Båda registren
ingick i en utvidgad databas bestående av 11 nationella register. Risk för
ljumskbråcksoperation efter radikal öppen operation för prostatacancer, efter
operation med titthålskirurgi för prostatacancer och efter strålning för
prostatacancer jämfördes med risken hos en kontrollgrupp bestående av män
utan prostatacancer, matchade för ålder och kön. Studien fann en trefaldig
ökning av ljumskbråckskirurgi efter operation för prostatacancer, oavsett
öppen eller titthålskirurgi.
Delarbete IV
Allvarliga komplikationer efter ljumskbråckskirurgi är få men potentiellt
livshotande. I SBR registreras peroperativa komplikationer som iakttagits
under operationen och i det nationella Patientregistret (NPR) registreras
diagnoskoder och operationskoder på patienter som vårdas inneliggande i
Sverige, liksom för dagkirurgiska operationer. SBR samkördes med PR för
att ta reda på antal patienter med allvarliga komplikationer i samband med
eller inom 30 dagar efter ljumskbråcksoperaton. I SBR fanns 815 noteringar
om komplikationer under operationen. I PR fann man 612 patienter som
drabbats av en hjärt-kärlkomplikation och 295 patienter med en eller flera
diagnoser tydande på allvarlig kirurgisk komplikation. Risk för hjärt-
kärlkomplikationer ökade vid hög ålder, grav allmän sjuklighet, akut
operation samt efter smärtlindring i form av ryggbedövning. Jämfört med
öppen främre nätteknik innebar alla andra kirurgiska teknikerna en ökad risk
för kirurgiska komplikationer.
Hanna Nilsson
39
Diskussion
Registerstudier kan identifiera ovanliga och allvarliga händelser under en
lång tidsperiod, något som inte låter sig göras med randomiserade studier.
Med hjälp av nationella register fann vi att ljumskbråckskirurgi är betydligt
vanligare efter radikal operation för prostatacancer än i normalbefolkningen,
något som bör föranleda diskussion mellan kirurger och urologer. Genom att
samköra svenskt bråckregister med flera andra register har vi belyst en rad
omständigheter och riskfaktorer för ökad dödlighet och svåra komplikationer
efter bråckkirurgi. Min förhoppning är att vetskapen härom kommer att
förbättra vården för patienter med ljumskbråck, särskilt kvinnor som söker
vård med tecken på tarmvred, där en noggrann undersökning kan vara
livsavgörande.
Mortality and Morbidity after Groin Hernia Surgery
40
Acknowledgement
I am deeply thankful to all friends, colleagues and family that have
contributed in various ways to this thesis and especially:
My supervisor Pär Nordin who have guided me through this thesis, step by
step, whether in Uganda or on Bear Safari in Jämtland
My co-supervisor Ulf Angerås, and former head of the Surgical department
of Sahlgrenska University Hospital/ Östra, for welcoming me to my present
working place and for encouragement when needed.
Hans Stenlund, my co-supervisor for showing me a completely different
world of science
Peter Naredi, former Professor in Umeå and now Professor at Sahlgrenska
University in Göteborg for believing in my project and for continuous
support
Annika Enarsson, register secretary of the Swedish Hernia Register. Without
you this thesis would not have been possible. Thank you for your thorough
work especially in Paper II, and for great fun in between.
Agneta Montgomery, Ursula Dahlstrand and all other board members of
Swedish Hernia Register for a warm welcome, and constant inspiration along
the way.
Pär Stattin, co-author, for sharing PCBaSe and for critically reviewing the
manuscript, more than once.
Gabriel Sandblom, co-author, for constructive criticism and enormous help
with the statistics.
Johan Stranne and other co-authors for making it a better thesis
Hanna Nilsson
41
The Department of Surgical and Perioperative Sciences in Umeå, particularly
Anna-Maria Lundgren. Without you I would have been completely lost in all
the logistics.
Anders Hyltander, present head of the surgical department, Sahlgrenska
University Hospital for making it a great place to work
All my coworkers at Östra sjukhuset, and especially all residents with whom
I have a lot of fun.
Eva Angenete, my supervisor at the clinic, who has been there for me through
many challenges and ethical discussions.
To all units participating in the Swedish Hernia Register. Without you this
thesis would certainly not have been possible.
To my parents for always believing in me, and teaching me that everything is
possible. A special thank to my father for your contagious enthusiasm for
science, your endless patience, and all your support.
To my sisters and brother with families, for giving me strength when deeply
needed.
And last but certainly not least, Ulf. If it weren’t for you this thesis would
have been finished years ago. Thank you for adding so much more to life!
Mortality and Morbidity after Groin Hernia Surgery
42
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Appendices (Papers I-IV)
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